Cutaneous manifestations in patients with mastocytosis: Consensus report of the European Competence Network on Mastocytosis; the American Academy of Allergy, Asthma & Immunology; and the European Academy of Allergology and Clinical Immunology

Mastocytosis is a condition characterized by expansion of clonal mast cells in various organ systems, often in association with activating KIT mutations. The organs most frequently affected are the skin and bone marrow. Traditionally, the disease is divided in cutaneous mastocytosis (CM) and systemic mastocytosis (SM). CM is further divided into maculopapular cutaneous mastocytosis (MPCM), also known as urticaria pigmentosa, diffuse cutaneous mastocytosis (DCM), and mastocytoma of skin. Children with mastocytosis usually have CM, whereas the majority of adults are diagnosed with SM. Both children and adults usually present with typical cutaneous (red or brown) lesions.

These cutaneous lesions are highly heterogeneous, encompassing local and disseminated forms. Overall there is a need for a better definition and a clinically meaningful classification of cutaneous lesions detectable in CM and SM. To address this need, an international task force of experts from the European Competence Network on Mastocytosis, the American Academy of Allergy, Asthma, and Immunology, and the European Academy of Allergology and Clinical Immunology met several times between 2010 and 2014. The resulting task force report published by Hartmann et al. in the current issue includes updated criteria for CM, a revised classification of cutaneous lesions, and related recommendations for daily practice (J Allergy Clin Immunol 2016; 137(1): 35-45).

Among other recommendations, the authors indicate that maculopapular cutaneous mastocytosis (urticaria pigmentosa) lesions should be subdivided into two distinct variants: a monomorphic variant characterized by small monomorphic maculopapular lesions that are typically found in adult patients, and a polymorphic variant with larger lesions of varying shape and size that are almost only detectable in children. Clinical experience suggests that the lesions of the monomorphic variant, when detected in children, always persist into adulthood, whereas the polymorphic lesions – when seen – usually fade away and disappear until puberty.

These observations highlight the prognostic value of a detailed inspection and subsequent classification of skin lesions in UP, and the related clinical implication for the management of patients in daily practice. Another recommendation of the task force group is that the Darier’s sign should be regarded as standard method for the evaluation and diagnosis of adult patients with mastocytosis with skin involvement.